A protest in Deraa today A protest in Deraa today, with people chanting \"there is only one God and Bashar is the enemy of God\".The Syrian Observatory for Human Rights says 473 people were killed during Ramadan (the first 29 days of August) , including 360 civilians and 113 members of the Syrian military and security forces. Twenty-eight people died under torture or in detention during the Muslim fasting month, the group said.
Activists say house raids are being carried out in Hama and Homs province.
The  Syrian Observatory for Human Rights says at least 16 people have been arrested in the town of Houla.
The United States has frozen the US assets and banned business transactions with Syrian Foreign Minister Walid al-Muallem and two other senior Syrian officials in response to Syria\'s increasingly violent crackdownagainst anti-government protesters.
The other two officials targeted by the latest sanctions were Syria\'s ambassador to Lebanon Ali Abdul Karim Ali and President Bashar al-Assad\'s adviser Bouthaina Shaaban.
\"We are bringing additional pressure to bear today directly on three senior Assad regime officials who are principle defenders of the regime\'s activities,\" David Cohen, Treasury\'s Under Secretary for Terrorism and Financial Intelligence, said in a statement on Tuesday.
\"This puts increased amount of pressure on those surrounding President Assad,\" Rosalind Jordan, Al Jazeera\'s correspondent in Washington, said.
\"All US citizens are now banned from conducting any transactions with these three [people],\" she said.
The new sanctions follow an August 18 order signed by President Barack Obama that froze all Syrian state assets inside the United States and forbade investment and exports to the country.
It also banned imports of oil and gas from Syria, aiming to hurt a key revenue stream for the Assad regime.
The attacks on protesters \"constitute an unusual and extraordinary threat to the national security, foreign policy and economy of the United States,\" the presidential order said.
At the same time Amnesty International says the use of torture in Syria has been \"widespread\" over many years
Amnesty International has said it believes that at least 88 people have died in detention in Syria during the past five months.
It says those who died, including 10 children, were subjected to beatings, burns, electric shocks and other abuse.
The group says it believes all of those who died were arrested after taking part in anti-government protests.
Foreign journalists have been blocked from entering Syria and the reports could not immediately be verified.
The allegations, published in a report, come shortly after the Syrian government denied persistent reports of at least one mass grave being uncovered in the restive southern city of Deraa.
\"These deaths behind bars are reaching massive proportions, and appear to be an extension of the same brutal disdain for life that we are seeing daily on the streets of Syria,\" said Neil Sammonds, Amnesty\'s researcher on Syria.
Mr Sammonds told the BBC that they have the names of at least 3,000 people who are currently in detention.
\"There are said to be 12-15,000 people detained in the country at the moment. We know that torture has been widespread over many years and it has got much much worse. Most people are held in incommunicado detention.\"
He said the volume of abuses, many of which had been documented on video and occurred near the cities of Homs and Deraa, had returned almost to levels not seen since the 1980s.
Deraa was the first Syrian city to see pro-democracy protests, in mid-March, and became an epicentre of the unrest after security forces launched a major operation to crush any dissent there. Dozens of people are believed to have been killed and hundreds arrested.
In its report, Amnesty said that the victims were all men or boys and, in at least 52 of the cases, there was evidence that torture or ill-treatment caused or contributed to the deaths.
Deaths in detention have also been reported in five other governorates - Damascus and Rif Damashq, Idlib, Hama and Aleppo, Amnesty said.
Amnesty International says it has compiled the names of more than 1,800 people reported to have died since pro-reform protests began. Thousands of others have been arrested, with many held incommunicado at unknown locations, according to the group.
Residents said that in the early hours of Wednesday morning Syrian troops backed by tanks raided houses looking for activists in two main districts of Hama.
A local activist told Reuters that several tanks were parked at a bridge at the eastern entrance to the city and then hundreds of troops entered two neighbourhoods on foot.
On Tuesday Syrian security forces cracked down on anti-government demonstrations in cities around the country Tuesday, as prayers marking the Muslim festival of Eid al-Fitr turned into protests, opposition sources said.
The opposition Local Coordination Committees of Syria said six people were killed in the city of Daraa, where a demonstration began at the Omari Mosque. One person died in Homs, said the LCC, which organizes and documents protests.
The anti-government activist group also reported hearing gunshots in the suburbs of the capital, Damascus, and said protests were broken up violently in Latakia, a center of the unrest that began in the spring.
The Syrian Observatory for Human Rights, a London-based opposition activist group, said a demonstration in Banias was met with intense gunfire from security forces. At least 30 people were detained, the observatory said.
Video appeared to show protesters in the western city of Homs mounting anti-government demonstrations after morning prayers, with large crowds denouncing Syrian President Bashar al-Assad.
CNN could not independently confirm the reports, and the Syrian government did not immediately comment.
Meanwhile, a Damascus resident who goes by the pseudonym Alexander Page said he saw no sign of the traditional Eid festivities in the city. \"No one\'s actually celebrating Eid. People are annoyed with people who celebrate Eid.\"
The shops that typically would stock up on sweets and Eid gifts were \"totally dead,\" he said.
Al-Assad attended Eid al-Fitr morning prayers in the capital, where the grand mufti of Damascus, a religious leader, gave a political sermon denouncing the \"enemies of Syria, who started to hatch unjust plots ... seditions, lies and fabrications,\" the government-run Syrian Arab News Agency, or SANA, reported.
Unrest has plagued Syria for more than five months, as protesters demanding more freedom, democratic elections and an end to al-Assad\'s regime have been met by brute force.
The government has maintained a consistent narrative: It is going after armed terrorists. But opposition activists say the regime is behind a systematic, sustained slaughter.
SANA reported Tuesday that \"an armed group\" kidnapped Attorney General Adnan Bakkour, his bodyguard and his driver Monday in Hama. Citing Hama police, SANA said the three were intercepted by seven gunmen armed with rifles and machine guns.
le -- mostly demonstrators -- have died since the uprising began in mid-March.
CNN is unable to independently confirm death tolls in Syria, which has restricted access to many parts of the country by international journalists.